Engineers at ArmaLite, then a budding arms company, designed and created the AR-10 and AR-15 in the mid-1950s. They gave them the “AR” designation as shorthand for “ArmaLite Rifle,” with the numbers referring to the rifles’ models. In case you were wondering what AR stands for, now you know.
In 1959, the company sold the rights for both types to firearms industry veteran Colt’s Manufacturing Company. They decided to keep the AR-15 name, which has stuck all this time. Other companies can now legally produce similar rifles, which are collectively referred to as “AR-15 style rifles.” Meanwhile, ArmaLite retains the AR-10 trademark.
These rifles were initially used by American soldiers in the 1960s, to counter the AK-47s of the North Vietnamese military and the Viet Cong. Colt would later offer semiautomatic versions for civilian use, which proved controversial at first. People eventually recognized them for their power, versatility, and customizability. According to CNN, “The AR-15 is now the most popular sporting rifle in the US.”